Capacitor-Based Insulation Resistance Monitoring for Electric Vehicles
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Solution Overview
Problem
Existing monitoring devices for hybrid and electric vehicles cannot efficiently detect and specify deteriorated insulation resistance parts during vehicle operation, leading to delayed identification of abnormalities and high recurrence probabilities.
Innovation Solution
A power-supply monitoring device with a capacitor-based charging/discharging system that detects insulation resistance deterioration by measuring capacitor voltages, allowing for real-time identification of abnormal parts even during vehicle operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pulse application system is used to detect insulation resistance deterioration, then the monitoring device can detect abnormalities, but the abnormal part cannot be specified until the vehicle is stopped
Solution Approach 1:
The system dynamically switches between monitoring mode (during vehicle operation) and specification mode (when vehicle is stopped) by controlling the switching element. This allows the system to adapt its functionality based on operational conditions, enabling continuous monitoring without requiring vehicle shutdown for specification.
Solution Approach 2:
The system performs preliminary monitoring of insulation resistance continuously during vehicle operation, so that when an abnormality occurs, the system is already prepared to quickly specify the abnormal part without waiting for vehicle shutdown. The monitoring data collected in advance accelerates the diagnostic process.
2Measurement precision
If the ignition is turned off to specify the deteriorated part of insulation resistance, then the abnormal part can be identified, but the vehicle cannot be restarted immediately for re-testing
Solution Approach 1:
The system maintains continuous monitoring of insulation resistance during vehicle operation through the capacitor-based circuit. The monitoring function operates continuously without interruption, allowing real-time detection while the vehicle is running, thus maintaining productivity while ensuring measurement capability.
3Loss of time
If a capacitor-based charging path is used for real-time monitoring, then abnormal parts can be specified during vehicle operation, but the system complexity increases
Solution Approach 1:
The capacitor and switching element serve multiple functions: they are part of the normal power management circuitry and simultaneously enable insulation resistance monitoring and abnormal part specification. This multi-functionality reduces the need for separate dedicated monitoring components, thereby limiting the increase in system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient specification of abnormal parts before the vehicle is stopped, improving accuracy and reducing recurrence probabilities of insulation-related issues.
Implementation Method 1
a capacitor (C1) that is serially connected to the fifth resistance (R5)
Implementation Method 2
detecting deterioration in insulation resistance of an electric power source
Data Source
AI summary
A power-supply monitoring device includes a capacitor that is connected to an insulated electric power source to execute charging/discharging. A power-supply monitoring device including this capacitor forms a charging path for detecting deterioration in an insulation resistance of an electric power source, and detects a voltage of the capacitor when being charged through this charging path. A vehicle controller specifies an abnormal part based on whether or not the voltage of the capacitor detected by the power-supply monitoring device is within a predetermined range.